Ink interconnect between print cartridge and carriage

ABSTRACT

In the preferred embodiment, an inkjet printer includes a replaceable print cartridge which is inserted into a scanning carriage. An ink tube extends from the scanning carriage to a separate ink supply located within the printer. A fluid interconnect on one side of the print cartridge connects to a fluid interconnect on the carriage when the print cartridge is inserted into the carriage to complete the fluid connection between the external ink supply and the print cartridge. In one embodiment, the fluid interconnection is made between the print cartridge and the ink tube simply by placing the print cartridge into a stall in the scanning carriage. The print cartridge has contact pads on another side. The contact pads electrically contact electrodes on the carriage when the print cartridge is placed in the stall. With the fluid interconnect and the contact pads on opposing sides of the print cartridge, the distance between the electrical contact and the flow of ink from the carriage to the print cartridge is maximized.

FIELD OF THE INVENTION

[0001] This invention relates to inkjet printers and, more particularly,to an inkjet printer having a scanning printhead with a stationary inksupply.

BACKGROUND OF THE INVENTION

[0002] Inkjet printers are well known. One common type of inkjet printeruses a replaceable print cartridge which contains a printhead and asupply of ink contained within the print cartridge. The print cartridgeis not intended to be refillable and, when the initial supply of ink isdepleted, the print cartridge is disposed of and a new print cartridgeis installed within the scanning carriage. Frequent replacement of theprint cartridge results in a relatively high operating cost.

[0003] The printhead has a useable life which is significantly longerthan the time it takes to deplete the ink within the print cartridge. Itis known to refill print cartridges intermittently by creating anopening through the print cartridge and manually refilling the printcartridge with ink. However, these refilling methods requiremanipulation by the user and are undesirable for various other reasons.

[0004] It is also known to provide an external, stationary ink reservoirconnected to the scanning print cartridge via a tube; however, thesetypes of printing systems have various drawbacks including undesirablefluctuations in ink pressure in the print cartridge, an unreliable andcomplex fluid seal between the print cartridge and the external inksupply, increased printer size due to the external ink supply'sconnection to the print cartridge, blockage in the ink delivery system,air accumulation in the tubes leading to the print cartridge, leakage ofink, high cost, and complexity.

[0005] What is needed is an improved inkjet printer with a replaceableprint cartridge and a separate ink delivery system connectable to theprint cartridge.

SUMMARY

[0006] In the preferred embodiment, an inkjet printer includes areplaceable print cartridge which is inserted into a scanning carriage.An ink tube extends from the scanning carriage to a separate ink supplylocated within the printer. A fluid interconnect on one side of theprint cartridge connects to a fluid interconnect on the carriage whenthe print cartridge is inserted into the carriage to complete the fluidconnection between the external ink supply and the print cartridge. Inone embodiment, the fluid interconnection is made between the printcartridge and the ink tube simply by placing the print cartridge into astall in the scanning carriage. The print cartridge has contact pads onanother side. The contact pads electrically contact electrodes on thecarriage when the print cartridge is placed in the stall. With the fluidinterconnect and the contact pads on opposing sides of the printcartridge, the distance between the electrical contact and the flow ofink from the carriage to the print cartridge is maximized.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1A is a perspective view of one embodiment of an inkjetprinter incorporating the present invention.

[0008]FIG. 1B is a top down view of another inkjet printer incorporatingthe present invention.

[0009]FIG. 2 is a perspective view of the ink delivery system andcarriage of another embodiment inkjet printer incorporating the presentinvention.

[0010]FIG. 3A illustrates the preferred carriage with one embodiment ofthe print cartridge in cross-section.

[0011]FIG. 3B is a perspective view looking down on a carriage with oneprint cartridge installed.

[0012]FIG. 3C illustrates the use of a flexible tube connected to arigid elbow member and to a manifold.

[0013]FIG. 3D is a top down view of a carriage incorporating theflexible tube of FIG. 3C.

[0014]FIG. 3E is a top down view of a carriage without a manifold andincorporating a flexible tube connected to a rigid elbow member.

[0015]FIG. 3F is a perspective view of a carriage without a manifold andincorporating a flexible tube connected to a rigid elbow member.

[0016]FIG. 4 is a detailed view of the interface between the flexibletubes connected to the external ink supply and the fluid interconnectlocated on the carriage.

[0017]FIG. 5A is a perspective view of the preferred print cartridge andthe fluid interconnect portion of the carriage.

[0018]FIG. 5B is another perspective view of the preferred printcartridge and fluid interconnect of the carriage.

[0019]FIG. 5C is a cross-sectional view of the print cartridge of FIG.5B now connected to the fluid interconnect on the carriage.

[0020]FIG. 6 is a simplified front view of the print head assembly on apreferred print cartridge.

[0021]FIG. 7 is a perspective view of the back side of the printheadassembly.

[0022]FIG. 8 is a cross-sectional view of the portion of the printcartridge containing the printhead assembly showing the flow of ink tothe ink ejection chambers in the printhead.

[0023]FIG. 9A is a perspective view of a scanning carriage incorporatingfour print cartridges in accordance with another embodiment of theinvention.

[0024]FIG. 9B is an ink supply station having ink supply cartridgesinstalled therein in accordance with one embodiment of the invention.

[0025]FIG. 10 is a perspective view of another embodiment printcartridge.

[0026]FIG. 11A is a side view of the print cartridge of FIG. 10connected to a fluid interconnect on the scanning carriage.

[0027]FIG. 11B illustrates a replaceable ink supply cartridge about toengage the ink refill port on the print cartridges of FIGS. 10 and 11Ain another embodiment printer.

[0028]FIG. 12A is a side view of the carriage of FIG. 9A.

[0029]FIG. 12B is a side view in partial cross-section of the ink supplystation in FIG. 9B.

[0030]FIG. 12C is a detailed view of the fluid interconnect portionlocated on the ink supply station for connection to an ink supplycartridge.

[0031]FIG. 13 is a perspective view of the two parts making up themanifold in the ink supply station.

[0032]FIG. 14 is a perspective view of the two parts making up themanifold in the scanning carriage.

[0033]FIG. 15 is a partial cutaway view of a print cartridge inaccordance with another embodiment of the invention.

[0034]FIGS. 16 and 17 illustrate the interconnection between the fluidinterconnect on the print cartridge of FIG. 15 and the fluidinterconnect on the scanning carriage.

[0035]FIG. 18 is a perspective view in partial cross-section of theprint cartridge of FIG. 15 illustrating an ink pressure regulator whichmay be internal to any of the print cartridges described herein.

[0036]FIG. 19 is a perspective view of the pressure regulatorsub-assembly of the print cartridge of FIG. 18 without the flexible airbag.

[0037]FIG. 20 is a perspective view of a pressure regulator lever in thepressure regulator sub-assembly of FIG. 19.

[0038]FIG. 21 is a perspective view of the opposite side of the pressureregulator lever of FIG. 20.

[0039]FIG. 22 is a perspective view of an accumulator lever of thepressure regulator sub-assembly of FIG. 19.

[0040]FIG. 23 is a perspective view of a fitment for the print cartridgeof FIG. 18.

[0041]FIG. 24 is a perspective view of the flexible bag and fitment forthe print cartridge of FIG. 18.

[0042]FIGS. 25 through 30 are diagrammatic views of the process formaking the flexible bag of FIG. 24.

[0043]FIG. 31 is a perspective view of the crown for the print cartridgeof FIG. 18.

[0044]FIG. 32 is a perspective view, partially cut away, of the crownand pressure regulator of FIG. 19 with the accumulator removed.

[0045]FIGS. 33 through 35 are side elevation views in partialcross-section illustrating the operation of the print cartridge of FIG.18.

[0046]FIG. 36A is an exploded view of a non-pressurized ink supplycartridge.

[0047]FIG. 36B is a cross-sectional view of a pressurized ink bag whichmay use the housing shown in FIG. 36A.

[0048]FIG. 36C is one embodiment of a spring used to provide a positivepressure on the ink bag in FIG. 36B.

[0049]FIG. 37 is an exploded view of an ink supply in accordance withone embodiment of the present invention.

[0050]FIG. 38 is a cross-sectional view, taken along line 38-38 of FIG.37, of a portion of the ink supply of FIG. 37.

[0051]FIG. 39 is a side view of the chassis of the ink supply of FIG.37.

[0052]FIG. 40 is a bottom view of the chassis of FIG. 39.

[0053]FIG. 41 is a top perspective view of the pressure plate of the inksupply of FIG. 37.

[0054]FIG. 42 is a bottom perspective view of the pressure plate of FIG.41.

[0055]FIG. 43 is an exploded, cross-sectional view of an alternativeembodiment of a pump for use in an ink supply in accordance with thepresent invention.

[0056]FIG. 44 shows the ink supply of FIG. 37 being inserted into adocking bay of an inkjet printer.

[0057]FIG. 45 is a cross-sectional view of a part of the ink supply ofFIG. 37 being inserted into the docking bay of an inkjet printer, takenalong line 45-45 of FIG. 44.

[0058]FIG. 46 is a cross-sectional view showing the ink supply of FIG.45 fully inserted into the docking bay.

[0059]FIG. 47 shows the docking bay of FIG. 44 with a portion of thedocking bay cutaway to reveal an out-of-ink detector.

[0060]FIGS. 48A through 48E are cross-sectional views of a portion ofthe ink supply and docking bay showing the pump, actuator, andout-of-ink detector in various stages of operation, taken along line48-48 of FIG. 47.

[0061]FIG. 49 is a perspective view of a facsimile machine showing oneembodiment of the ink delivery system in phantom outline.

[0062]FIG. 50 is a perspective view of a copier, which may be a combinedfacsimile machine and printer, illustrating one embodiment of the inkdelivery system in phantom outline.

[0063]FIG. 51 is a perspective view of a large-format inkjet printerillustrating one embodiment of the ink delivery system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Overview of PrinterEmbodiments

[0064]FIG. 1A is a perspective view of one embodiment of an inkjetprinter 10, with its cover removed, incorporating various inventivefeatures. Generally, printer 10 includes a tray 12 for holding virginpaper. When a printing operation is initiated, a sheet of paper fromtray 12 is fed into printer 10 using a sheet feeder, then brought aroundin a U direction to now travel in the opposite direction toward tray 12.The sheet is stopped in a print zone 14, and a scanning carriage 16,containing one or more print cartridges 18, is then scanned across thesheet for printing a swath of ink thereon.

[0065] After a single scan or multiple scans, the sheet is thenincrementally shifted using a conventional stepper motor and feedrollers 20 to a next position within print zone 14, and carriage 16again scans across the sheet for printing a next swath of ink. When theprinting on the sheet is complete, the sheet is forwarded to a positionabove tray 12, held in that position to ensure the ink is dry, and thenreleased.

[0066] Alternative embodiment printers include those with an output traylocated at the back of printer 10, where the sheet of paper is fedthrough the print zone 14 without being fed back in a U direction.

[0067] The carriage 16 scanning mechanism may be conventional andgenerally includes a slide rod 22, along which carriage 16 slides, and acoded strip 24 which is optically detected by a photodetector incarriage 16 for precisely positioning carriage 16. A stepper motor (notshown), connected to carriage 16 using a conventional drive belt andpulley arrangement, is used for transporting carriage 16 across printzone 14.

[0068] The novel features of inkjet printer 10 and the other inkjetprinters described in this specification relate to the ink deliverysystem for providing ink to the print cartridges 18 and ultimately tothe ink ejection chambers in the printheads. This ink delivery systemincludes an off-axis ink supply station 30 containing replaceable inksupply cartridges 31, 32, 33, and 34, which may be pressurized or atatmospheric pressure. For color printers, there will typically be aseparate ink supply cartridge for black ink, yellow ink, magenta ink,and cyan ink.

[0069] Four tubes 36 carry ink from the four replaceable ink supplycartridges 31-34 to the four print cartridges 18.

[0070] Various embodiments of the off-axis ink supply, scanningcarriage, and print cartridges will be described herein.

[0071]FIG. 1B is a top down view of another printer 10 very similar tothat shown in FIG. 1A, but with the paper tray removed. An electricalconnector 37 is shown connected between printer 10 and a personalcomputer. Elements throughout the various figures identified with thesame numerals may be identical.

[0072]FIG. 2 illustrates the ink delivery system of an alternativeembodiment printer 40. In this embodiment, four replaceable ink supplycartridges 42-45 are shown installed in a fixed station 46 above ascanning carriage 48. This particular location of station 46 and thehorizontal arrangement of ink supply cartridges 42-45 results in anefficient utilization of available space within printer 40. In anotherembodiment, station 46 may be located virtually anywhere within printer40.

[0073] A single print cartridge 50 is shown installed in carriage 48.Four tubes 36, each connected to an ink supply cartridge 42-45, are influid connection with a rubber septum 52 for each of the four stalls incarriage 48. A hollow needle 60 (FIG. 3A) formed as part of each printcartridge 50 is inserted through the rubber septum 52 upon pushing theprint cartridge 50 into its associated stall within carriage 48 so thata fluid communication path exists between a particular ink supplycartridge 42-45 and a particular print cartridge 50 for providing asupply of ink to the print cartridge 50.

[0074] A sheet of paper enters through the bottom portion of printer 40in the direction of arrow 53, then guided back in a U direction, andtransported through the print zone 14 in the direction of arrow 54.Carriage 48 then scans across print zone 14 for printing on the sheet.In another embodiment, a sheet of paper enters the print zone 14 in thedirection of arrow 53.

[0075] Elements previously designated and described will not beredundantly described.

Description of Carriage and Print Cartridge Embodiments

[0076]FIG. 3A is a perspective view looking up at carriage 48, showingprint cartridge 50 and septum 52 in cross-section. This cross-sectiondoes not show a regulator valve within print cartridge 50 that regulatespressure by opening and closing hole 65. An opening in the bottom ofcarriage 48 exposes the printhead location 58 of each print cartridge50. Carriage electrodes 49 oppose contact pads located on printcartridge 50.

[0077] When the aforementioned regulator valve is opened, a hollowneedle 60 is in fluid communication with an ink chamber 61 internal toprint cartridge 50. The hollow needle 60 extends through a self-sealingslit formed through the center of septum 52. This self-sealing slit isautomatically sealed by the resiliency of the rubber septum 52 whenneedle 60 is removed.

[0078] A plastic ink conduit 62 leads from needle 60 to ink chamber 61via hole 65. Conduit 62 may also be integral to the print cartridgebody. Conduit 62 may be glued, heat-staked, ultrasonically welded, orotherwise secured to the print cartridge body.

[0079] Ink is provided to carriage 48 by tubes 36 which connect to aplastic manifold 66. Tubes 36 may be formed of Polyvinylidene Chloride(PVDC), such as Saran™, or other suitable plastic. Tubes 36 may also beformed of a very flexible polymer material and dipped in PVDC forreducing air diffusion through the tubes. In the preferred embodiment,non-pressurized ink tubes 36 have an internal diameter betweenapproximately 1.5-2.5 mm, while pressurized ink tubes 36 have aninternal diameter between approximately 1-1.5 mm. Manifold 66 providesseveral 90 redirections of ink flow. Such a manifold 66 may not beneeded if tubes 36 are sufficiently slender and can be bent withoutbuckling. A pressurized off-axis ink supply (described later) mayutilize such slender tubing. An alternative to manifold 66 is a seriesof elbows molded or formed out of heat formed tubing.

[0080] A septum elbow 71 routes ink from manifold 66 to septum 52 andsupports septum 52. Septum 52 is affixed to elbow 71 using a crimp cap73.

[0081] A bellows 67 (shown in cross-section) is provided for each of theindividual stalls 68 for allowing a degree of x, y, and z movement ofseptum 52 when needle 60 is inserted into septum 52 to minimize the x,y, and z load on needle 60 and ensure a fluid-tight and air-tight sealaround needle 60. Bellows 67 may be formed of butyl rubber, high acnnitrile, or other flexible material with low vapor and air transmissionproperties. Bellow 67 can be any length and can even be a flexiblediaphram.

[0082] A spring 70 urges septum 52 upward. This allows septum 52 to takeup z tolerances, minimizes the load on needle 60, and ensures a tightseal around needle 60.

[0083] Slots 72 formed on each of the stalls 68 in carriage 48 alignwith tabs on each print cartridge 50 to restrict movement of the printcartridge 50 within the stall 68.

[0084] An air vent 74 formed in the top of print cartridge 50 is used bya pressure regulator in print cartridge 50, to be described later. In analternative embodiment, a separate regulator may be connected betweenthe off-axis ink supply and each print cartridge 50.

[0085]FIG. 3B is a perspective view of carriage 48 looking down oncarriage 48 and showing one print cartridge 50 installed.

[0086] In other embodiments, shown in FIGS. 3C-3F, bellows 67 isreplaced with a U-shaped, circular, or straight flexible tube.

[0087]FIG. 3C illustrates a circular flexible tube 63 connected betweenelbow 71 and manifold 66.

[0088]FIG. 3D is a top down view of the carriage 16 incorporating tube63.

[0089] In another embodiment, shown in FIG. 3E, manifold 66 is deleted,and tubes 63 are connected to (or are part of) tube 36. A plastic guide64 may be used to guide the tubes 63.

[0090] In FIG. 3F, the tubes 36 are directly connected to the rigidplastic elbow 71 supporting septum 52 without being coiled.

[0091] If desired, the print cartridges can be secured within thescanning carriage by individual latches, which may be manually operatedor spring loaded, where the latches press down on a tab or a corner ofthe print cartridge. In another embodiment, a single latch, such as ahinged bar, secures all four print cartridges in place within thecarriage.

[0092]FIG. 4 is a detailed view of manifold 66, tubes 36, crimp cap 73,septum 52, septum elbow 71, spring 70, and bellows 67 described withrespect to FIG. 3A. A stress reliever 77 for tubes 36 is also shown.

[0093]FIG. 5A is a perspective view of one embodiment of print cartridge50. A shroud 76 (also shown in FIG. 3B) surrounds needle 60 (obscured byshroud 76) to prevent inadvertent contact with needle 60 and also tohelp align septum 52 (FIG. 3A) with needle 60 when installing printcartridge 50 in carriage 48.

[0094] Coded tabs 79 align with coded slots in the carriage stalls 68 toensure the proper color print cartridge 50 is placed in the proper stall68. In another embodiment, coded tabs 79 are located on shroud 76.

[0095] A flexible tape 80 containing contact pads 86 leading to theprinthead substrate is secured to print cartridge 50. These contact pads86 align with and electrically contact electrodes 49 (FIG. 3A) oncarriage 48. Preferably, the electrodes on carriage 48 are resilientlybiased toward print cartridge 50 to ensure a reliable contact. Suchcarriage electrodes are found in U.S. Pat. No. 5,408,746, entitled DatumFormation for Improved Alignment of Multiple Nozzle Members in aPrinter, by Jeffrey Thoman et al., assigned to the present assignee andincorporated herein by reference.

[0096] The printhead nozzle array is at location 58. An integratedcircuit chip 78 provides feedback to the printer regarding certainparameters of print cartridge 50.

[0097]FIG. 5B illustrates the bottom side of print cartridge 50. Twoparallel rows of offset nozzles 82 are shown laser ablated through tape80. An ink fill hole 81 is used to initially fill print cartridge 50with ink. A stopper (not shown) is intended to permanently seal hole 81after the initial filling.

[0098]FIG. 5C is a cross-sectional view of print cartridge 50, withouttape 80, taken along line 5C-5C in FIG. 5A. Shroud 76 is shown having aninner conical or tapered portion 75 to receive septum 52 and centerseptum 52 with respect to needle 60. In an alternative embodiment,needle 60 is part of a separate subassembly, and shroud 76 is a separatesubassembly, for manufacturing ease and to allow color key changing bychanging the shroud, assuming the color key tabs are located on theshroud.

[0099] The print cartridges and ink supply connections described thusfar are down-connect types where the ink connection is made whenpressing the print cartridge down into the carriage. This enables aresulting printer to have a very low profile since the ink path does notextend above the print cartridge. In various embodiments shown havingthe needle extending from the print cartridge, the needle may bereplaced with a septum, and the septum on the scanning carriage replacedwith a hollow needle.

[0100]FIGS. 6, 7, and 8 illustrate the basic principles of the printheadassembly 83. Printhead assembly 83 is preferably a flexible polymer tape80 (FIG. 5B) having nozzles 82 formed therein by laser ablation.Conductors 84 (FIG. 7) are formed on the back of tape 80 and terminatein contact pads 86 for contacting electrodes on carriage 48. The otherends of conductors 84 are bonded through windows 87 to terminals of asubstrate 88 (FIG. 7) on which are formed the various ink ejectionchambers and ink ejection elements. The ink ejection elements may beheater resistors or piezoelectric elements. The printhead assembly maybe similar to that described in U.S. Pat. No. 5,278,584, by Brian Keefe,et al., entitled “Ink Delivery System for an Inkjet Printhead,” assignedto the present assignee and incorporated herein by reference. In such aprinthead assembly, ink within print cartridge 50 flows around the edgesof the rectangular substrate 88 and into ink channels 90 leading to eachof the ink ejection chambers.

[0101]FIG. 8 illustrates the flow of ink 92 from the ink chamber 61within print cartridge 50 to ink ejection chambers 94. Energization ofthe ink ejection elements 96 and 98 cause a droplet of ink 101, 102 tobe ejected through the associated nozzles 82. A photoresist barrierlayer 104 defines the ink channels and chambers, and an adhesive layer106 affixes the flexible tape 80 to barrier layer 104. Another adhesive108 provides a seal between tape 80 and the plastic print cartridge body110. In one embodiment, a wall 112 separates the ink flow paths aroundthe two edges of substrate 88, and a different color ink is supplied toeach side of wall 112.

[0102] The conductor portion of the flexible tape 80 is glued orheat-staked to the print cartridge body 110.

[0103] A demultiplexer on substrate 88 demultiplexes the incomingelectrical signals applied to contact pads 86 and selectively energizesthe various ink ejection elements to eject droplets of ink from nozzles82 as printhead 79 scans across the print zone. In one embodiment, thedots per inch (dpi) resolution is 300 dpi, and there are 300 nozzles 82.In another embodiment, at least the black ink cartridge prints at aresolution of 600 dpi.

[0104]FIG. 9A is a perspective view of another embodiment scanningcarriage 120 having four print cartridges 122-125 installed. One of theprint cartridges 122 is shown in FIG. 10. Tubes 36 from an off-axis inksupply station 128 (FIG. 9B) supply ink to a manifold 130 whichredirects the ink to a 90 interface cap 132 for each of print cartridges122-125. Preferably, each cap 132 is of a color similar to the color inkwithin each print cartridge 122-125. This embodiment differs from thatshown in FIG. 3A in that the ink is coupled to print cartridges 122-125by pressing a septum 133 (FIG. 11) down onto a hollow needle 134 (FIG.10) extending from the top of the print cartridge 122, rather thanpressing a needle 60 (FIG. 3A) down into the septum 52 (FIG. 3A). Alsoshown in FIG. 10 are air vent 74 for an internal pressure regulator,coded tabs 135 for ensuring the proper color print cartridge isinstalled in the proper carriage stall, and the location 58 of theprinthead.

[0105] In the particular embodiment shown in FIG. 9B, only three out ofthe four color ink supply cartridges 136-139 are installed in ink supplystation 128. A hollow needle 142 extending from a stall in the inksupply station 128, to be described in greater detail with respect toFIGS. 12B and 12C, is in fluid communication with one of tubes 36. Theink within each of ink supply cartridges 136-139 is at atmosphericpressure, and ink is drawn into each of print cartridges 122-125 by anegative pressure within each print cartridge 122-125 determined by aregulator internal to each print cartridge.

[0106] In another embodiment, to be described later, the off-axis inksupply cartridges are pressurized. In both the pressurized andunpressurized ink supply embodiments, the regulator internal to eachprint cartridge regulates the pressure of ink supplied to the printcartridge.

[0107] In another embodiment, shown in FIG. 11B, the print cartridges122 installed in carriage 120 have ink supply cartridges 139 connecteddirectly to needle 134, so that carriage 120 supports the printcartridges 122 and the ink supply cartridges 139. A septum on the inksupply cartridges 139 connect to needle 134 in a manner similar to thatshown in FIG. 11A. The ink supply cartridges 139 are preferably made tohave a low profile to achieve a low profile printer.

[0108]FIG. 12A is a side view of the carriage 120 and print cartridgeassembly of FIG. 9A connected to the off-axis ink supply station 128 viatubes 36.

[0109]FIG. 12B is a cross-sectional view of ink supply cartridge 138 inthe off-axis ink supply station 128 taken along line 12B-12B in FIG. 9B.As seen, a hollow needle 142 extending in an upward direction from theink supply support 144 is inserted through a rubber septum 146 on inksupply cartridge 138 to create a fluid communication path between theink reservoir 148 within ink supply cartridge 138 and one ink conduitwithin manifold 150. In one embodiment, ink reservoir 148 comprises acollapsible ink bag, to be described later. The ink conduits withinmanifold 150 are coupled to tubes 36 which connect to the various printcartridges within scanning carriage 120.

[0110]FIG. 12C is a detailed view of needle 142 extending from the inksupply station 128. Also shown are a spring-loaded humidor 145, having arubber portion 145′ which covers needle hole 147 when the ink supplycartridge 138 is removed, and a plastic elbow 149 connected to tube 36.Elbows 149 replace manifold 150 (FIG. 12B) in the embodiment of FIG.12C.

[0111]FIG. 13 is a perspective view of manifold 150 in the off-axis inksupply station 128 of FIG. 12B. Manifold 150 is opened to reveal theinternal ink conduits 152-155.

[0112]FIG. 14 is a perspective view of the four ink conduits 156 inmanifold 130 on the scanning carriage 120 of FIG. 9A for redirecting theflow of ink from tubes 36 to print cartridges 122-125 in FIG. 9A.

[0113]FIG. 15 is perspective view of another embodiment print cartridge158 in partial cross-section.

[0114] Print cartridge 158 of FIG. 15 may be similar to any one of printcartridges 122-125 shown in FIG. 9A except that, instead of having aneedle protruding from a top surface of the print cartridge, printcartridge 158 has a rubber septum 160 for receiving a hollow needle.Print cartridge 158 is to be installed in a carriage similar to carriage120 in FIG. 9A. An axial passage 162 communicates between a central slitformed in septum 160 and an ink chamber 164 within print cartridge 158.A cap 166 is crimped onto neck 168 and onto septum 160 to form a sealbetween septum 160 and the remainder of the print cartridge 158. Thecrimping of cap 166 also serves to compress septum 160 so as to ensurethe central slit is sealed.

[0115] The flexible tape 80 forming a part of the printhead assembly isshown revealed on a side of print cartridge 158. Contact pads 86 forconnection to electrodes on a carriage are also shown.

[0116]FIG. 16 illustrates the fluid interconnect between an ink supplytube 36 and septum 160 of print cartridge 158. Tube 36, connected to anoff-axis ink supply, is fitted over a hollow needle 170. Needle 170 ispreferably 18-gage stainless steel having a diameter of about 1.2 mm. Ahousing 172 on the scanning carriage houses a spring 174 and a slidinghumidor consisting of a rigid plastic collar 176 and a compliant innerportion 178. A pocket 180 in the compliant inner portion 178 reduces thefriction between the compliant inner portion 178 and needle 170. In FIG.16, print cartridge 158 is installed in the carriage prior to the fluidinterconnect being made.

[0117]FIG. 17 shows the completed fluid interconnect between theoff-axis ink supply and print cartridge 158 after the fluid interconnectsystem on the carriage has been brought down onto print cartridge 158.The downward force of the fluid interconnect system compresses spring174 while causing needle 170 to be inserted through a central slit inseptum 160. The compliant inner portion 178 and rubber septum 160 are incontact with one another. Ink now flows from the off-axis ink supplystation, through tube 36, through hollow needle 170, through hole 182formed in hollow needle 170, through axial passage 162, and into theprint cartridge's ink chamber 164 (FIG. 15).

[0118] In another embodiment, needle 170 directly extends from areplaceable ink supply cartridge, such as from ink supply cartridge 139in FIG. 11B, and the ink supply cartridge and print cartridges 158 aresupported by the scanning carriage.

[0119] The central slit formed in septum 160 creates an air-tight sealaround needle 170. The slit becomes sealed when needle 170 is withdrawnfrom septum 160.

[0120] Print cartridge 158 is thus supplied with ink from the off-axisink supply station.

[0121] Thus, a number of print cartridge embodiments and inkinterconnections between an off-axis ink supply and the print cartridgehave been shown.

Description of Regulator Internal to Print Cartridges

[0122] FIGS. 18-35 describe a pressure regulator which may be usedwithin any of the print cartridge embodiments described herein forregulating the pressure of the ink chamber within the print cartridge.Hence, the pressure in the off-axis ink supply system may beunregulated. The regulator causes the ink chamber within the printcartridge to have a slight, but substantially constant, negativepressure (e.g., −2 to −7 inches of water column) to prevent ink droolfrom the nozzles of the printhead. If the off-axis ink supply system isat atmospheric pressure, this slight negative pressure in the printcartridge also acts to draw ink from the off-axis ink supply system evenif the location of the ink supply system is slightly below the printcartridge. The regulator also enables the use of pressurized off-axisink supplies while maintaining the desired negative pressure within theink chamber in the print cartridge. The regulator can be designed toprovide a wide range of negative pressures (or back pressures) from 0 to−50 inches of water column, depending on the design of the printhead.

[0123] In the embodiments shown in FIGS. 18-35, the regulator isdescribed with reference to the type of print cartridge similar to printcartridge 158 in FIG. 15 having a septum 235 (FIG. 18); however, it isto be understood that a regulator using similar concepts may also beused with any of the other print cartridge embodiments.

[0124] Referring to FIG. 18, reference numeral 214 generally indicatesthe print cartridge that includes a pen body 242 that is the housing forthe cartridge and a crown 243 that forms a cap to the housing. Locatedat a remote end of the pen body is the tab head assembly 244 or THA. TheTHA includes a flex circuit 245 and a silicon die 246 that forms theprint head 240. The THA is of conventional construction. Also locatedwithin the pen body 242 is a pressure regulator lever 248, anaccumulator lever 250, and a flexible bag 252. In FIG. 18, the bag isillustrated fully inflated and for clarity is not shown in FIG. 19. Thepressure regulator lever 248 and the accumulator lever 250 are urgedtogether by a spring 253, 253′ illustrated in FIG. 19. In opposition tothe spring, the bag spreads the two levers apart as it inflates outward.The bag is staked to a fitment 254 that is press-fit into the crown 243.The fitment contains a vent 255 to ambient pressure in the shape of ahelical, labyrinth path. The vent connects and is in fluid communicationwith the inside of the bag so that the bag is maintained at a referencepressure. The helical path limits the diffusion of water out of the bag.

[0125] The pressure regulator lever 248 is illustrated in detail inFIGS. 20 and 21. Reference numeral 257 generally indicates the locationof the area where the bag 252 directly bears against the lever. Thelever 248 rotates about two opposed axles 258 that form the axis ofrotation of the lever. The rotation of the lever is stopped when thelever engages the pen body 242 as illustrated in FIG. 35. The axles arelocated at the ends of cantilevers 259 formed by deep slots so that thecantilevers and the axles can be spread apart during manufacture andsnapped onto place on the crown 243 as illustrated in FIG. 32.Perpendicular to the plane of the regulator lever 248 is a valve seat261 and a valve seat holder 262. The valve seat is pressed into place onthe holder and is fabricated from a resilient material. In response toexpansion and contraction of the bag 252, the regulator lever 248rotates about the axles 258, 258′ and causes the valve seat to open andshut against a mating surface on the crown 243 as described below. Thisrotational motion controls the flow of ink into the ink plenum 238, FIG.34. There is an optimization between maximizing the force on the valveseat and obtaining sufficient motion of the lever. In the embodimentactually constructed, the lever ratio between the distance between thecentroid of the lever, generally at point 257, and the axles 258 and thedistance between the center of the valve seat and the axles 258 isbetween two to one and five to one with four to one being preferred. Thepressure regulator also includes a spring boss 264 and engages thespring 253, FIG. 19. The spring boss is protected during manufacture bytwo shoulders 265 which are not illustrated in FIG. 19.

[0126] The accumulator lever 250 is illustrated in FIG. 22 and includesan actuation area 268 where the bag 252 directly bears against thelever. The lever rotates about two opposed axles 270, 270′ that form anaxis of rotation of the accumulator lever. The axles are remotelylocated on cantilevers 271 so that the axles and the cantilevers can bespread apart during manufacture and snapped into place on the crown 243as described below. The accumulator lever also includes a spring boss272 that engages the other end of the spring 253, FIG. 19. Like thespring boss 64 on the pressure regulator, the boss 272 on theaccumulator is protected during manufacture by the shoulders 273. Theseshoulders are not illustrated in FIG. 19.

[0127] The accumulator lever 250 and the bag 252 operate together toaccommodate changes in volume due to any air that may be entrapped inthe print cartridge 214, as well as due to any other pressure changes.The accumulator acts to modulate any fluctuations in the back pressure.The accumulator lever squeezes the bag the inside of which is at ambientpressure, forces air out of the bag and allows air trapped in the printcartridge to expand.

[0128] Although most of the accumulation is provided by the movement ofthe accumulator lever 250 and the bag 252, there is additionalaccumulation provided by the pressure regulator lever 248 in cooperationwith the resilient valve seat 261, FIG. 20. The valve seat acts as aspring and allows some movement of the regulator lever 248 while thevalve is shut. In other words, as the back pressure in the plenum 238(FIG. 34) decreases, the bag 252 exerts less force on the levers, andthe spring 253 urges the levers together. The motion of the regulatorlever compresses the valve seat and the regulator lever shuts a littlefurther. This movement of the regulator lever 248 with the bag 252results in some additional air accommodation.

[0129] It should be appreciated that the boss 272 on the accumulatorlever 250 is closer to the axis of rotation of the accumulator leverthan the boss 264, FIGS. 20 and 21, on the pressure regulator lever isto its axis of rotation. This difference in distance causes theaccumulator lever to actuate before the pressure regulator lever moves.

[0130] The accumulator lever 250 rotates about the axles 270 until astop 275 on the lever engages a surface 276 within the crown 243, asillustrated in FIG. 31. The stop prevents the lever from moving tooclose and interfering with the pressure regulator lever 248 when theback pressure in the ink plenum drops. The accumulator lever rotates inthe other direction until coming into contact with the pen body 242 asillustrated in FIGS. 34 and 35.

[0131] Referring to FIG. 19, reference numeral 253 generally indicates ahelical extension spring that urges the two levers 248, 250 together.The spring is preloaded and engages the bosses 264, 272 with a coil loopat each distal end. Each loop is a parallel, cross-over, fully closed,centered loop. This spring is designed to have the least amount ofvariation in its force constant over its full range of travel so thatthe back pressure can be regulated as closely as possible.

[0132] The fitment 254, illustrated in FIGS. 18 and 23, supports the bag252 and attaches the bag to the crown 243. The fitment has a lip 278that engages the crown and forms a hermetic seal with it. Within thefitment is a vent 255 that provides communication between the interiorof the bag and ambient pressure. At the distal end of the fitment is araised, circular boss 279 and a race-track shaped outer boss 280. Thebag 252 is staked to both bosses. The circular boss provides the mainseal between the bag and the fitment. The race-track shaped bossprovides a secondary, redundant sealing surface as well as providesadditional support and positioning for the bag.

[0133] The flexible bag 252, illustrated in FIGS. 18 and 24, expands andcontracts as a function of the differential pressure between the backpressure in the ink plenum 238 (FIG. 34) and ambient pressurecommunicated through the vent 255 in the fitment 254. The bag is shownfully inflated in FIG. 24. The bag is designed to push against the twolevers 248, 250 with maximum contact area through the entire range oftravel of the levers. The bag is formed from a single sheet ofmultilayer film and includes two lungs 282 that expand and contractabout an axis 284. The lungs communicate with each other and aremaintained at the same reference pressure. Each lung has two raisedareas 283 on either side so that there are four raised areas in all. Thetwo inner raised areas that bear against each other are not shown inFIG. 24 but are indicated by reference numerals 283′ and 283″. The sideopposite the fitment contains a raised communication channel 285, FIGS.26, 28, between the raised areas which allows a path for air to flowwhen the bag is completely deflated. The raised areas are thinner thatthe rest of the bag and provide greater compliance to the travel of thelevers and the motion of the lungs about the axis 284. The raised areasare designed to eliminate relative motion or sliding of the bag withrespect to the levers. In systems that actuate on very slight pressures,this undesirable affect is called hysteresis. The combination of thelungs and raised areas provides extra material into which the bag canexpand as well as maximizes the change in ink volume displaced by thebag with any change in differential pressure.

[0134] The process for making the bag 252 is illustrated in FIGS. 25-30.First, a sheet 287 of flat film is cut to size, FIG. 25. The film is amultilayer structure between one and three mils (one rail is 25.4microns) thick, 1.5 mils being the preferred thickness. In the preferredembodiment, three materials show acceptable performance: (1)PE/tie/PVDC/tie/PE, (2) PE/tie/PVDF/tie/PE, and (3) PE/tie/EVOH/tie/PE.PVDC is polyvinylidene chloride; DOW version is known as SARAN. EVOH isethylene-vinyl alcohol copolymer. PE is polyethylene. Tie is a layerused to bond the dissimilar materials together. PVDF ispolyvinylidenefluoride and is sold under the trade name of Kynar™. Next,the sheet is placed over a die plate, and heat and vacuum are applied toform the four raised areas 288, 288′, FIG. 26. Note that two of the fourraised areas or pockets 288′ are in communication. Thereafter, the sheet287 is heat staked to the two bosses 279, 280 on the fitment 254, FIG.23, as shown in FIG. 27. Next, a hole 289 is made in the film in thecenter of the circular boss 279 to establish communication to the vent255 in the fitment. The sheet is then folded along axis 290 and theperimeter of the bag where the margins came together is staked. Thisstaking occurs along the three open seams and is indicated by referencenumeral 291 in FIG. 29. The perimeter of the bag is then trimmed.Thereafter, the bag is folded along the longitudinal axis 296 of thefitment as illustrated in FIG. 29. This forms the two lungs 282, 282′ inthe bag. Referring to FIGS. 29, 30, and 24, the longitudinal axis 296 ofthe fitment and the line of folding in FIG. 29 is parallel to the axis284 of rotation of the two lungs including expansion/contraction of thebag.

[0135]FIG. 31 illustrates the bottom-side of the crown 243 whichincludes a valve face 293 and the tapered nozzle or orifice 292 throughwhich ink enters the plenum 238. The valve face mates with the valveseat 261, FIG. 20, on the pressure regulator lever 248. This mating isalso shown in FIG. 32. Ink flows through the fluid interconnect, theseptum 235, and the orifice 292. The tapered orifice 292 reduces thearea of contact between the valve seat 261 and the valve face 293 tothereby increase the valve sealing pressure.

[0136] At orifice 292, the back pressure within the plenum 238 (FIG. 34)is controlled by the lever 248. Next to the valve face 293 on the crown243 is a circular boss 294 that receives the lip 278 on the fitment 254,FIG. 24. The boss 294 and the lip form a hermetic seal. The axles 258,258′, FIG. 21, on the pressure regulator lever 248 are snapped into thejournals 295, 295′ as permitted by the cantilevered constructiondescribed above. In like manner the axles 270, 270′ on the accumulatorlever 250 are received in the journals 297, 297′, FIG. 31. Also locatedon the bottom side of the crown is the surface 276 that engages the stop275, FIG. 22, on the accumulator lever 250. The stop 275 and the surface276 prevent the accumulator lever from interfering with the pressureregulator lever 248.

[0137] The operation of the print cartridge 214 is illustrated in FIGS.33, 34, and 35. In the initial condition of the cartridge, there is noink within the ink plenum 238, and the bag 252 is limp. The backpressure in the plenum equals ambient pressure. The spring 253 urges thetwo levers 248, 250 fully together.

[0138] Next, a hollow needle is inserted into the septum 235 and avacuum is drawn on the nozzles in the print head 240 (FIG. 18) to drawink into the print cartridge. In response to this vacuum, theaccumulator lever 250 moves first, and the bag begins to expand as shownin FIG. 24. The accumulator lever continues to rotate about its axis ofrotation until it engages the side wall of the pen body 242 as shown inFIG. 24. At this point the pressure regulator lever 248 begins to move,and ink begins to enter the plenum 238 through orifice 292, FIG. 31.

[0139] The regulator lever 248 can rotate about its axis of rotationuntil it engages the side wall of the pen body 242 as shown in FIG. 35.This is the full-open position of the valve. The regulator lever movesbetween the states illustrated in FIGS. 34 and 35 depending on the speedof printing and how fast ink is required by the print head.

[0140] Once the plenum 238 is filled with ink or printing has stopped,the pressure regulator lever 248 will slowly rotate and close theorifice at the urging of the spring 253. The levers 248 and 250 returnto the state illustrated in FIG. 34 which is the normal or steady statecondition of the print cartridge. This state occurs just prior to orsubsequent to printing.

[0141] Referring to FIG. 34, reference numeral 298 indicates an airbubble that has entered the ink plenum 238. If the print cartridge issubjected to an elevation in temperature or increased altitude, the airbubble will expand in the plenum. The expansion of the air bubble willbe compensated for by the contraction of the bag 252 due to a pressurechange caused by a volume change of the bubble which in turn causes theaccumulator lever to move from the state illustrated in FIG. 34 towardthat illustrated in FIG. 33. In addition, there will be someaccompanying motion of the regulator lever 248 because of the resilienceof the valve seat 261. On the other hand, if the air bubble contracts,the bag will expand in response and the pressure regulator lever 248will open the orifice and admit ink onto the plenum. In other words, anyexpansion or contraction of an air bubble will cause the bag tocompensate in reverse, that is by contracting to expansion and expandingto contraction. Each of the levers tracks the motion of the bag and theaccumulator lever 250 rotates before the regulator lever 248 because ofthe difference in lever arm distances.

[0142] When the off-axis ink supply (e.g., supply 30 in FIG. 1) isdepleted of ink, the levers 248, 250 rotate to the full-open position inFIG. 35 and the print head stops ejecting ink.

Description of the Off-Axis Ink Delivery System

[0143]FIG. 36A is an exploded view of a non-pressurized ink supplycartridge 300 such as shown in FIGS. 2, 9B, and 12B. Such an ink supplycartridge 300 is simply removed from the ink supply support (e.g.,support 144 in FIG. 12B) and disposed of once its supply of ink has beendepleted. The connection of such an ink supply cartridge 300 to thefluid interconnect has been described with respect to FIG. 12B.

[0144] The non-pressurized ink supply cartridge 300 consists of acollapsible ink bag 302 and two rigid plastic housing members 303 and304. Ink bag 302 may be formed of a flexible film such as Mylar or EVA,or a multi-layer film similar to the plastic sheet 350 described withrespect to FIG. 37 or the nine-layer film described in U.S. Pat. No.5,450,112, assigned to the present assignee and incorporated herein byreference. The ends of inkbag 302 may be heat-staked or ultrasonicallywelded to housing member 303 or 304 to limit movement of bag 302.

[0145] Coded tabs 305 align with slots formed in the ink supply supportto ensure the proper color ink supply cartridge is inserted into thecorrect stall of the ink supply support. In one embodiment, the inksupply support also latches onto tab 305, using a spring-loaded latch,to secure cartridge 300 and to provide tactile feedback to the user thatcartridge 300 is properly installed.

[0146] A plastic ink bag fitment 306 is partially inserted through anopening 307 in ink bag 302 and sealed with respect to opening 307 byglue or heat fusing. A poppet 308 extends from fitment 306. Bag fitment306 is held firmly in place by a slot 307 formed in the plastic housingmembers 303 and 304.

[0147] A poppet spring 309 is inserted through a hole 310 in poppet 308followed by a poppet ball 311. Ball 311 may be stainless steel orplastic.

[0148] An end 312 of a rubber septum 313 is then inserted into hole 310in poppet 308. Septum 313 is then crimped and secured to poppet 308using a crimped cap 314.

[0149] Septum 313 has a slit 315 formed through its center through whicha hollow needle 142 (FIG. 12B), in fluid connection with a printcartridge, is inserted as shown in FIG. 12B. Slit 315 in septum 313 isautomatically urged closed by the resiliency of septum 313 when theneedle is removed.

[0150] Poppet spring 309 and poppet ball 311 serve to provide addedassurance that no ink will leak through slit 315 in septum 313. Whenthere is no needle inserted through slit 315, poppet spring 309 urgespoppet ball 311 against the closed slit 315 so that ball 311 inconjunction with the closing of slit 315 provides a seal against inkleakage. Further description of this type of double-sealing valve isprovided with respect to the pressurized ink supply cartridge embodimentshown in FIG. 37.

[0151] It is possible to design the fluid interconnect using a septumwithout the poppet, or a poppet without the septum. A septum without thepoppet will reliably seal around a needle with a radial seal. However,when the ink supply with a septum has been installed in the printer fora long time, the septum will tend to take on a compression set. Uponremoval, the septum may not completely reseal itself. If the supply istipped or dropped, ink may leak out. A poppet valve (by itself) has theadvantage (relative to a septum) of self-sealing without a compressionset issue. However, it is less reliable in that it does not seal aroundthe needle. Thus, to ensure a leak-tight fluid interconnection with thecartridge, some kind of face seal must be established. In addition,poppet valves vary in reliability when the surface they seal against ishard plastic—small imperfections in the sealing surface tend to lead toleaks. The combination of the septum/poppet valve overcomes theselimitations by utilizing the advantages of both: the septum's very goodsealing around the needle while eliminating the compression set issue.Additionally, the inside surface of the septum provides a compliantsealing surface for the poppet valve that is less sensitive toimperfections.

[0152] In the preferred embodiment, an integrated circuit sensor/memory316 is permanently mounted to ink supply cartridge 300. This circuitprovides a number of functions, including verifying insertion of the inksupply, providing indication of remaining ink in the supply, andproviding a code to assure compatibility of the ink supply with the restof the system.

[0153] In an alternate embodiment, ink bag 302 is provided with apositive pressure. This enables the tubes connecting the ink supply tothe print cartridges to be thinner and also allows the ink supplystation to be located well below the print cartridges. FIG. 36B is across-sectional view of ink supply cartridge 300 along line 36B-36B inFIG. 36A illustrating how a spring 317 urges the sides of ink bag 302together to create a positive internal pressure. Ink bag 302 is providedwith rigid side panels 318 to distribute the spring force. Bow springs,spiral springs, foam, a gas, or other resilient devices may supply thespring force. Ink 319 is shown within ink bag 302. FIG. 36C is a topdown view of one embodiment of spring 317 formed as a stainless steelspiral.

[0154] In another embodiment, ink bag 302 may be pressurized by anintermittent pressure source, such as a gas.

[0155] FIGS. 37-48E illustrate a pressurized off-axis ink supplycartridge and an apparatus for pressurizing the ink supply cartridge.

[0156]FIG. 37 is an exploded view of ink supply 320.

[0157] The ink supply 320 has a chassis 322 which carries an inkreservoir 324 for containing ink, a pump 326, and fluid outlet 328. Thechassis 322 is enclosed within a hard protective shell 330 having a cap332 affixed to its lower end. The cap 332 is provided with an aperture334 to allow access to the pump 326 and an aperture 336 to allow accessto the fluid outlet 328.

[0158] To use the ink supply 320, it is inserted into a docking bay 338of an ink-jet printer, as illustrated in FIGS. 1 and 44-47. Uponinsertion of the ink supply 320, an actuator 340 within the docking bay338 is brought into contact with the pump 326 through aperture 334. Inaddition, a fluid inlet 342 within the docking bay 338 is coupled to thefluid outlet 328 through aperture 336 to create a fluid path from theink supply to the printer. Operation of the actuator 340 causes the pump326 to draw ink from the reservoir 324 and supply the ink through thefluid outlet 328 and the fluid inlet 342 to the printer.

[0159] Upon depletion of the ink from the reservoir 324, or for anyother reason, the ink supply 320 can be easily removed from the dockingbay 338. Upon removal, the fluid outlet 328 and the fluid inlet 342 areclosed to help prevent any residual ink from leaking into the printer oronto the user. The ink supply may then be discarded or stored forreinstallation at a later time. In this manner, the present ink supply320 provides a user of an ink-jet printer a simple, economical way toprovide a reliable and easily replaceable supply of ink to an ink-jetprinter.

[0160] As illustrated in FIGS. 37-40, the chassis 322 has a main body344. Extending upward from the top of the chassis body 344 is a frame346 which helps define and support the ink reservoir 324. In theillustrated embodiment, the frame 346 defines a generally squarereservoir 324 having a thickness determined by the thickness of theframe 346 and having open sides. Each side of the frame 346 is providedwith a face 348 to which a sheet of plastic 350 (FIG. 37) is attached toenclose the sides of the reservoir 324. The illustrated plastic sheet isflexible to allow the volume of the reservoir to vary as ink is depletedfrom the reservoir. This helps to allow withdrawal and use of all of theink within the reservoir by reducing the amount of back pressure createdas ink is depleted from the reservoir. The illustrated ink supply 320 isintended to contain about 30 cubic centimeters of ink when full.Accordingly, the general dimensions of the ink reservoir defined by theframe are about 57 millimeters high, about 60 millimeters wide, andabout 5.25 millimeters thick. These dimensions may vary depending on thedesired size of the ink supply and the dimensions of the printer inwhich the ink supply is to be used.

[0161] In the illustrated embodiment, the plastic sheets 350 are heatstaked to the faces 348 of the frame in a manner well known to those inthe art. The plastic sheets 350 are, in the illustrated embodiment,multi-ply sheets having an outer layer of low density polyethylene, alayer of adhesive, a layer of metallized polyethylene terephthalate, alayer of adhesive, a second layer of metallized polyethyleneterephthalate, a layer of adhesive, and an inner layer of low densitypolyethylene. The layers of low density polyethylene are about 0.0005inches thick and the metallized polyethylene terephthalate is about0.00048 inches thick. The low density polyethylene on the inner andouter sides of the plastic sheets can be easily heat staked to the framewhile the double layer of metallized polyethylene terephthalate providesa robust barrier against vapor loss and leakage. Of course, in otherembodiments, different materials, alternative methods of attaching theplastic sheets to the frame, or other types of reservoirs might be used.

[0162] The body 344 of the chassis 322, as seen in FIGS. 37-40, isprovided with a fill port 352 to allow ink to be introduced into thereservoir. After filling the reservoir, a plug 354 (FIG. 38) is insertedinto the fill port 352 to prevent the escape of ink through the fillport. In the illustrated embodiment, the plug is a polypropylene ballthat is press fit into the fill port.

[0163] A pump 326 is also carried on the body 344 of the chassis 322.The pump 326 serves to pump ink from the reservoir and supply it to theprinter via the fluid outlet 328. In the illustrated embodiment, seen inFIGS. 37 and 38, the pump 326 includes a pump chamber 356 that isintegrally formed with the chassis 322. The pump chamber is determinedby a skirt-like wall 358 which extends downwardly from the body 344 ofthe chassis 322.

[0164] A pump inlet 360 is formed at the top of the chamber 356 to allowfluid communication between the chamber 356 and the ink reservoir 324. Apump outlet 362 through which ink may be expelled from the chamber 356is also provided. A valve 364 is positioned within the pump inlet 360.The valve 364 allows the flow of ink from the ink reservoir 324 into thechamber 356 but limits the flow of ink from the chamber 356 back intothe ink reservoir 324. In this way, when the chamber is depressurized,ink may be drawn from the ink reservoir, through the pump inlet and intothe chamber When the chamber is pressurized, ink within the chamber maybe expelled through the pump outlet.

[0165] In the illustrated embodiment, the valve 364 is a flapper valvepositioned at the bottom of the pump inlet. The flapper valve 364illustrated in FIGS. 37 and 38, is a rectangular piece of flexiblematerial. The valve 364 is positioned over the bottom of the pump inlet360 and heat staked to the chassis 322 at the midpoints of its shortsides (the heat staked areas are darkened in the Figures). When thepressure within the chamber drops sufficiently below that in thereservoir, the unstaked sides of the valve each flex downward to allowthe flow of ink around the valve 364, through the pump inlet 360 andinto the chamber 356. In alternative embodiments, the flapper valvecould be heat staked on only one side so that the entire valve wouldflex about the staked side, or on three sides so that only one side ofthe valve would flex. Other types of valves may also be suitable.

[0166] In the illustrated embodiment the flapper valve 364 is made of atwo ply material. The top ply is a layer of low density polyethylene0.0015 inches thick. The bottom ply is a layer of polyethyleneterephthalate (PET) 0.0005 inches thick. The illustrated flapper valve364 is approximately 5.5 millimeters wide and 8.7 millimeters long. Ofcourse, in other embodiments, other materials or other types or sizes ofvalves may be used.

[0167] A flexible diaphragm 366 encloses the bottom of the chamber 356.The diaphragm 366 is slightly larger than the opening at the bottom ofthe chamber 356 and is sealed around the bottom edge of the wall 358.The excess material in the oversized diaphragm allows the diaphragm toflex up and down to vary the volume within the chamber. In theillustrated ink supply, displacement of the diaphragm allows the volumeof the chamber 356 to be varied by about 0.7 cubic centimeters. Thefully expanded volume of the illustrated chamber 356 is between about2.2 and 2.5 cubic centimeters.

[0168] In the illustrated embodiment, the diaphragm 366 is made of thesame multi-ply material as the plastic sheets 350. Of course, othersuitable materials may also be used to form the diaphragm. The diaphragmin the illustrated embodiment is heat staked, using conventionalmethods, to the bottom edge of the skirt-like wall 358. During the heatstaking process, the low density polyethylene in the diaphragm seals anyfolds or wrinkles in the diaphragm to create a leak proof connection.

[0169] A pressure plate 368 and a spring 370 are positioned within thechamber 356. The pressure plate 368, illustrated in detail in FIGS. 41and 42, has a smooth lower face 372 with a wall 374 extending upwardabout its perimeter. The central region 376 of the pressure plate 368 isshaped to receive the lower end of the spring 370 and is provided with aspring retaining spike 378. Four wings 380 extend laterally from anupper portion of the wall 374. The illustrated pressure plate is moldedof high density polyethylene.

[0170] The pressure plate 368 is positioned within the chamber 356 withthe lower face 372 adjacent the flexible diaphragm 366. The upper end ofthe spring 370, which is stainless steel in the illustrated embodiment,is retained on a spike 382 formed in the chassis and the lower end ofthe spring 370 is retained on the spike 378 on the pressure plate 368.In this manner, the spring biases the pressure plate downward againstthe diaphragm to increase the volume of the chamber. The wall 374 andwings 380 serve to stabilize the orientation of the pressure plate whileallowing for its free, piston-like movement within the chamber 356. Thestructure of the pressure plate, with the wings extending outward fromthe smaller face, provides clearance for the heat stake joint betweenthe diaphragm and the wall and allows the diaphragm to flex withoutbeing pinched as the pressure plate moves up and down. The wings arealso spaced to facilitate fluid flow within the pump.

[0171] An alternative embodiment of the pump 326 is illustrated in FIG.43. In this embodiment, the pump includes a chamber 356 a defined by askirtlike wall 358 a depending downwardly from the body 344 a of thechassis. A flexible diaphragm 366 a is attached to the lower edge of thewall 358 a to enclose the lower end of the chamber 356 a. A pump inlet360 a at the top of the chamber 356 a extends from the chamber 356 ainto the ink reservoir and a pump outlet 362 a allows ink to exit thechamber 356 a. The pump inlet 360 a has a wide portion 386 opening intothe chamber 356 a, a narrow portion 388 opening into the ink reservoir,and a shoulder 390 joining the wide portion 386 to the narrow portion388. A valve 364 a is positioned in the pump inlet 360 a to allow theflow of ink into the chamber 356 a and limit the flow of ink from thechamber 356 a back into the ink reservoir. In the illustrated embodimentthe valve is circular. However, other shaped valves, such as square orrectangular, could also be used.

[0172] In the embodiment of FIG. 43, a unitary spring/pressure plate 392is positioned within the chamber 356 a. The spring/pressure plate 392includes a flat lower face 394 that is positioned adjacent the diaphragm366 a, a spring portion 396 that biases the lower face downward, and amounting stem 398 that is friction fit into the wide portion 386 of thepump inlet. In the illustrated embodiment, the spring portion 396 isgenerally circular in configuration and is pre-stressed into a flexedposition by the diaphragm 366 a. The natural resiliency of the materialused to construct the spring/pressure plate urges the spring to itsoriginal configuration, thereby biasing the lower face downward toexpand the volume of the chamber 356 a. The unitary spring/pressureplate 392 may be formed of various suitable materials such as, forexample, HYTREL™.

[0173] In this embodiment, the valve 364 a is a flapper valve that isheld in position on the shoulder 390 of the pump inlet 360 a by the topof the mounting stem 398. The mounting stem 398 has a cross shaped crosssection which allows the flapper valve 364 a to deflect downward intofour open quadrants to allow ink to flow from the ink reservoir into thechamber. The shoulder prevents the flapper valve from deflecting in theupward direction to limit the flow of ink from the chamber back into thereservoir. Rather, ink exits the chamber via the pump outlet 362. Itshould be appreciated that the mounting stem may have a ‘V’ crosssection, an ‘I’ cross section, or any other cross section which allowsthe flapper valve to flex sufficiently to permit the needed flow of inkinto the chamber.

[0174] As illustrated in FIG. 38, a conduit 384 joins the pump outlet362 to the fluid outlet 328. In the illustrated embodiment, the top wallof the conduit 384 is formed by the lower member of the frame 346, thebottom wall is formed by the body 344 of the chassis, one side isenclosed by a portion of the chassis and the other side is enclosed by aportion of one of the plastic sheets 350. As illustrated in FIGS. 37 and38, the fluid outlet 328 is house within a hollow cylindrical boss 399that extends downward from the chassis 322. The top of the boss 399opens into the conduit 384 to allow ink to flow from the conduit intothe fluid outlet. A spring 400 and sealing ball 402 are positionedwithin the boss 399 and are held in place by a compliant septum 404 anda crimp cover 406. The length of the spring 400 is such that it can beplaced into the inverted boss 399 with the ball 402 on top. The septum404 and can then inserted be into the boss 399 to compress the spring400 slightly so that the spring biases the sealing ball 402 against theseptum 404 to form a seal. The crimp cover 406 fits over the septum 404and engages an annular projection 408 on the boss 399 to hold the entireassembly in place.

[0175] In the illustrated embodiment, both the spring 100 and the ball402 are stainless steel. The sealing ball 402 is sized such that it canmove freely within the boss 399 and allow the flow of ink around theball when it is not in the sealing position. The septum 404 is formed ofpolyisoprene rubber and has a concave bottom to receive a portion of theball 402 to form a secure seal. The septum 404 is provided with a slit410 so that it may be easily pierced without tearing or coring. However,the slit is normally closed such that the septum itself forms a secondseal. The slit may, preferably, be slightly tapered with its narrowerend adjacent the ball 402. The illustrated crimp cover 406 is formed ofaluminum and has a thickness of about 0.020 inches. A hole 412 isprovided so that the crimp cover 406 does not interfere with thepiercing of the septum 404.

[0176] With the pump and fluid outlet in place, the ink reservoir 324can be filled With ink. To fill the ink reservoir 324, ink can beinjected through the fill port 352. As ink is being introduced into thereservoir, a needle (not shown) can be inserted through the slit 410 inthe septum 404 to depress the sealing ball 402 and allow the escape ofany air from within the reservoir. Alternatively, a partial vacuum canbe applied through the needle. The partial vacuum at the fluid outletcauses ink from the reservoir 324 to fill the chamber 356, the conduit384, and the cylindrical boss 399 such that little, if any, air remainsin contact with the ink. The partial vacuum applied to the fluid outletalso speeds the filling process. Once the ink supply is filled, the plug354 is press fit into the fill port to prevent the escape of ink or theentry of air.

[0177] Of course, there are a variety of other methods which might alsobe used to fill the present ink supply. In some instances, it may bedesirable to flush the entire ink supply with carbon dioxide prior tofilling it with ink. In this way, any gas trapped within the ink supplyduring the filling process will be carbon dioxide, not air. This may bepreferable because carbon dioxide may dissolve in some inks while airmay not. In general, it is preferable to remove as much gas from the inksupply as possible so that bubbles and the like do not enter the printhead or the trailing tube. To this end, it may also be preferable to usedegassed ink to further avoid the reaction or presence of bubbles in theink supply.

[0178] Although the ink reservoir 324 provides an ideal way to containink, it may be easily punctured or ruptured and may allow some amount ofwater loss from the ink. Accordingly, to protect the reservoir 324 andto further limit water loss, the reservoir 324 is enclosed within aprotective shell 330. In the illustrated embodiment, the shell 330 ismade of clarified polypropylene. A thickness of about one millimeter hasbeen found to provide robust protection and to prevent unacceptablewater loss from the ink. However, the material and thickness of theshell may vary in other embodiments.

[0179] As illustrated in FIG. 37, the top of the shell 330 has contouredgripping surfaces 414 that are shaped and textured to allow a user toeasily grip and manipulate the ink supply 320. A vertical rib 416 havinga detente 418 formed near its lower end projects laterally from eachside of the shell 330. The base of the shell 330 is open to allowinsertion of the chassis 322. A stop 420 extends laterally outward fromeach side of the wall 358 that defines the chamber 356. These stops 420abut the lower edge of the shell 330 when the chassis 322 is inserted.

[0180] A protective cap 332 is fitted to the bottom of the shell 330 tomaintain the chassis 322 in position. The cap 332 is provided withrecesses 428 which receive the stops 420 on the chassis 322. In thismanner, the stops are firmly secured between the cap and the shell tomaintain the chassis in position. The cap is also provided with anaperture 334 to allow access to the pump 326 and with an aperture 336 toallow access to the fluid outlet 328. The cap 332 obscures the fill portto help prevent tampering with the ink supply.

[0181] The cap is provided with projecting keys 430 which can identifythe type of printer for which the ink supply is intended and the type ofink contained within the ink supply. For example, if the ink supply isfilled with black ink, a cap having keys that indicate black ink may beused. Similarly, if the ink supply is filled with a particular color ofink, a cap indicative of that color may be used. The color of the capmay also be used to indicate the color of ink contained within the inksupply.

[0182] As a result of this structure, the chassis and shell can bemanufactured and assembled without regard to the particular type of inkthey will contain. Then, after the ink reservoir is filled, a capindicative of the particular ink used is attached to the shell. Thisallows for manufacturing economies because a supply of empty chassis andshells can be stored in inventory. Then, when there is a demand for aparticular type of ink, that ink can be introduced into the ink supplyand an appropriate cap fixed to the ink supply. Thus, this schemereduces the need to maintain high inventories of ink supplies containingevery type of ink.

[0183] In the illustrated embodiment, the bottom of the shell 330 isprovided with two circumferential grooves 422 which engage twocircumferential ribs 424 formed on the cap 332 to secure the cap to theshell. Sonic welding or some other mechanism may also be desirable tomore securely fix the cap to the shell. In addition, a label (not shown)can be adhered to both the cap and the shell to more firmly secure themtogether. In the illustrated embodiment, pressure sensitive adhesive isused to adhere the label in a manner that prevents the label from beingpeeled off and inhibits tampering with the ink supply.

[0184] The attachment between the shell, the chassis and the cap should,preferably, be snug enough to prevent accidental separation of the capfrom the shell and to resist the flow of ink from the shell should theink reservoir develop a leak. However, it is also desirable that theattachment allow the slow ingress of air into the shell as ink isdepleted from the reservoir to maintain the pressure inside the shellgenerally the same as the ambient pressure. Otherwise, a negativepressure may develop inside the shell and inhibit the flow of ink fromthe reservoir. The ingress of air should be limited, however, in orderto maintain a high humidity within the shell and minimize water lossfrom the ink.

[0185] In the illustrated embodiment, the shell 330 and the flexiblereservoir 324 which it contains have the capacity to hold approximatelythirty cubic centimeters of ink. The shell is approximately 67millimeters wide, 15 millimeters thick, and 60 millimeters high. Ofcourse, other dimensions and shapes can also be used depending on theparticular needs of a given printer.

[0186] The illustrated ink supply 320 is ideally suited for insertioninto a docking station 432 like that illustrated in FIGS. 44-47. Thedocking station 432 illustrated in FIG. 44, is intended for use with acolor printer. Accordingly, it has four side-by-side docking bays 338,each of which can receive one ink supply 320 of a different color. Thestructure of the illustrated ink supply allows for a relatively narrowwidth. This allows for four ink supplies to be arranged side-by-side ina compact docking station without unduly increasing the footprint of theprinter.

[0187] Each docking bay 338 includes opposing walls 434 and 436 whichdefine inwardly facing vertical channels 438 and 440. A leaf spring 442(FIG. 45) having an engagement prong 444 is positioned within the lowerportion of each channel 438 and 440. The engagement prong 444 of eachleaf spring 442 extends into the channel toward the docking bay 338 andis biased inward by the leaf spring. The channels 438 and 440 areprovided with mating keys 439 formed therein. In the illustratedembodiment, the mating keys in the channels on one wall are the same foreach docking bay and identify the type of printer in which the dockingstation is used. The mating keys in the channels of the other wall aredifferent for each docking bay and identify the color of ink for use inthat docking bay. A base plate 446 defines the bottom of each dockingbay 338. The base plate 446 includes an aperture 448 which receives theactuator 340 and carries a housing 450 for the fluid inlet 342.

[0188] As illustrated in FIG. 44, the upper end of the actuator extendsupward through the aperture 448 in the base plate 446 and into thedocking bay 338. The lower portion of the actuator 340 is positionedbelow the base plate and is pivotally coupled to one end of a lever 452which is supported on pivot point 454. The other end of the lever 454 isbiased downward by a compression spring 456 (FIG. 47). In this manner,the force of the compression spring 456 urges the actuator 340 upward. Acam 458 (FIG. 48A) mounted on a rotatable shaft 460 is positioned suchthat rotation of the shaft to an engaged position causes the cam toovercome the force of the compression spring 456 and move the actuator340 downward. Movement of the actuator, as explained in more detailbelow, causes the pump 326 to draw ink from the reservoir 324 and supplyit through the fluid outlet 328 and the fluid inlet 342 to the printer.

[0189] As illustrated in FIG. 47, a flag 484 extends downward from thebottom of the actuator 340 where it is received within an opticaldetector 486. The optical detector 486 is of conventional constructionand directs a beam of light from one leg 486 a toward a sensor (notshown) positioned on the other 486 b leg. The optical detector ispositioned such that when the actuator 340 is in its uppermost position,corresponding to the top of the pump stroke, the flag 484 raises abovethe beam of light allowing it to reach the sensor and activate thedetector. In any lower position, the flag blocks the beam of light andprevents it from reaching the sensor and the detector is in adeactivated state. In this manner, the sensor can be used, as explainedmore fully below, to control the operation of the pump and to detectwhen an ink supply is empty.

[0190] As seen in FIG. 45, the fluid inlet 342 is positioned within thehousing 450 carried on the base plate 446. The illustrated fluid inlet342 includes an upwardly extending needle 462 having a closed, bluntupper end 464, a blind bore 466 and a lateral hole 468. A trailing tube469, seen in FIG. 47, is connected to the lower end of the needle 462 influid. communication with the blind bore 466. The trailing tube 469leads to a print head (not shown). In most printers, the print head willusually include a small ink well for maintaining a small quantity of inkand some type of pressure regulator to maintain an appropriate pressurewithin the ink well. Typically, it is desired that the pressure withinthe ink well be slightly less than ambient. This back pressure helps toprevent ink from dripping from the print head. The pressure regulator atthe print head may commonly include a check valve which prevents thereturn flow of ink from the print head and into the trailing tube.

[0191] A sliding collar 470 surrounds the needle 462 and is biasedupwardly by a spring 472. The sliding collar 470 has a compliant sealingportion 474 with an exposed upper surface 476 and an inner surface 478into direct contact with the needle 462. In addition, the illustratedsliding collar includes a substantially rigid portion 480 extendingdownwardly to partially house the spring 472. An annular stop 482extends outward from the lower edge of the substantially rigid portion480. The annular stop 482 is positioned beneath the base plate 446 suchthat it abuts the base plate to limit upward travel of the slidingcollar 470 and define an upper position of the sliding collar on theneedle 462. In the upper position, the lateral hole 468 is surrounded bythe sealing portion 474 of the collar to seal the lateral hole and theblunt end 464 of the needle is generally even with the upper surface 476of the collar.

[0192] In the illustrated embodiment, the needle 462 is an eighteengauge stainless steel needle with an inside diameter of about 1.04millimeters, an outside diameter of about 1.2 millimeters, and a lengthof about 30 millimeters. The lateral hole is generally rectangular withdimensions of about 0.55 millimeters by 0.70 millimeters and is locatedabout 1.2 millimeters from the upper end of the needle. The sealingportion 474 of the sliding collar is made of ethylene propylene timermonomer and the generally rigid portion 476 is made of polypropylene orany other suitably rigid material. The sealing portion is molded with anaperture to snugly receive the needle and form a robust seal between theinner surface 478 and the needle 462. In other embodiments, alternativedimensions, materials or configurations might also be used.

[0193] To install an ink supply 320 within the docking bay 338, a usercan simply place the lower end of the ink supply between the opposingwalls 434 and 436 with one edge in one vertical channel 438 and theother edge in the other vertical channel 440, as shown in FIG. 44. Theink supply is then pushed downward into the installed position, shown inFIG. 46, in which the bottom of the cap 332 abuts the base plate 446. Asthe ink supply is pushed downward, the fluid outlet 328 and fluid inlet342 automatically engage and open to form a path for fluid flow from theink supply to the printer, as explained in more detail below. Inaddition, the actuator enters the aperture 334 in the cap 332 topressurize the pump, as explained in more detail below.

[0194] Once in position, the engagement prongs 444 on each side of thedocking station engage the detentes 418 formed in the shell 330 to fullyhold flue ink supply in place. The leaf springs 442, which allow theengagement prongs to move outward during insertion of the ink supply,bias the engagement prongs inward to positively hold the ink supply inthe installed position. Throughout the installation process and in theinstalled position, the edges of the ink supply 320 are captured withinthe vertical channels 438 and 440 which provide lateral support andstability to the ink supply. In some embodiments, it may be desirable toform grooves in one or both of the channels 438 and 440 which receivethe vertical rib 416 formed in the shell to provide additional stabilityto the ink supply.

[0195] To remove the ink supply 320, a user simply grasps the inksupplying the contoured gripping surfaces 414, and pulls upward toovercome the force of the leaf springs 442. Upon removal, the fluidoutlet 328 and fluid inlet 342 automatically disconnect and resealleaving little, if any, residual ink, and the pump 326 is depressurizedto reduce the possibility of any leakage from the ink supply.

[0196] Operation of the fluid interconnect, that is the fluid outlet 328and the fluid inlet 342, during insertion of the ink supply isillustrated in FIGS. 45 and 46. FIG. 45 shows the fluid outlet 328 uponits initial contact with the fluid inlet 342. As illustrated in FIG. 45,the housing 450 has partially entered the cap 332 through aperture 336,and the lower end of the fluid outlet 328 has entered into the top ofthe housing 450. At this point, the crimp cover 406 contacts the sealingcollar 470 to form a seal between the fluid outlet 328 and the fluidinlet 342 while both are still in their sealed positions. This seal actsas a safety barrier in the event that any ink should leak through theseptum 404 or from the needle 462 during the coupling and are couplingprocess.

[0197] In the illustrated configuration, the bottom of the fluid inletand the top of the fluid outlet are similar in shape. Thus, very littleair is trapped within the seal between the fluid outlet of the inksupply and the fluid inlet of the printer. This facilitates properoperation of the printer by reducing the possibility that air will enterthe fluid outlet 328 or the fluid inlet 342 and reach the ink jets inthe print head.

[0198] As the ink supply 320 is inserted further into the docking bay338, the bottom of the fluid outlet 328 pushes the sliding collar 470downward, as illustrated in FIG. 46. Simultaneously, the needle 462enters the slit 410 and passes through the septum 404 to depress thesealing ball 402. Thus, in the fully inserted position, ink can flowfrom the boss 399, around the sealing ball 402, into the lateral hole468, down the bore 466, through the trailing tube 469 to the print head.

[0199] Upon removal of the ink supply 320, the needle 462 is withdrawnand the spring 400 presses the sealing ball 402 firmly against theseptum to establish a robust seal. In addition, the slit 410 closes toestablish a second seal, both of which serve to prevent ink from leakingthrough the fluid outlet 328. At the same time, the spring 472 pushesthe sliding collar 470 back to its upper position in which the lateralhole 468 is encased within the sealing portion of the collar 474 toprevent the escape of ink from the fluid inlet 342. Finally, the sealbetween the crimp cover 406 and the upper surface 476 of the slidingcollar is broken. With this fluid interconnect, little, if any, ink isexposed when the fluid outlet 328 is separated from the fluid inlet 342.This helps to keep both the user and the printer clean.

[0200] Although the illustrated fluid outlet 328 and fluid inlet 342provide a secure seal with little entrapped air upon sealing and littleexcess ink upon unsealing, other fluid interconnections might also beused to connect the ink supply to the printer. For example, theillustrated fluid inlet could be located on the ink supply and theillustrated fluid outlet could be located in the docking bay.

[0201] As illustrated in FIG. 46, when the ink supply 320 is insertedinto the docking bay 338, the actuator 340 enters through the aperture334 in the cap 332 and into position to operate the pump 326. FIGS.48A-E illustrate various stages of the pump's operation. FIG. 48Aillustrates the fully charged position of the pump 326. The flexiblediaphragm 366 is in its lowermost position, the volume of the chamber356 is at its maximum, and the flag 484 is blocking the light beam fromthe sensor. The actuator 340 is pressed against the diaphragm 366 by thecompression spring 456 to urge the chamber to a reduced volume andcreate pressure within the pump chamber 356. As the valve 364 limits theflow of ink from the chamber back into the reservoir, the ink passesfrom the chamber through the pump outlet 362 and the conduit 384 to thefluid outlet 328. In the illustrated embodiment, the compression springis chosen so as to create a pressure of about 1.5 pounds per square inchwithin the chamber. Of course, the desired pressure may vary dependingon the requirements of a particular printer and may vary throughout thepump stroke. For example, in the illustrated embodiment, the pressurewithin the chamber will vary from about 90-45 inches of water columnduring the pump stroke.

[0202] As ink is depleted from the pump chamber 356, the compressionspring 456 continues to press the actuator 340 upward against thediaphragm 366 to maintain a pressure within the pump chamber 356. Thiscauses the diaphragm to move upward to an intermediate positiondecreasing the volume of the chamber, as illustrated in FIG. 48B. In theintermediate position, the flag 484 continues to block the beam of lightfrom reaching the sensor in the optical detector 486.

[0203] As still more ink is depleted from the pump chamber 356, thediaphragm 340 is pressed to its uppermost position, illustrated in FIG.48C. In the uppermost position, the volume of the chamber 356 is at itsminimum operational volume and the flag 484 rises high enough to allowthe light beam to reach the sensor and activate the optical detector486.

[0204] The printer control system (not shown) detects activation of theoptical detector 486 and begins a refresh cycle. As illustrated in FIG.48D, during the refresh cycle the cam 458 is rotated into engagementwith the lever 452 to compress the compression spring 456 and move theactuator 340 to its lowermost position. In this position, the actuator340 does not contact the diaphragm 366.

[0205] With the actuator 340 no longer pressing against the diaphragm366, the pump spring 370 biases the pressure plate 368 and diaphragm 366outward, expanding the volume and decreasing the pressure within thechamber 356. The decreased pressure within the chamber 356 allows thevalve 364 to open and draws ink from the reservoir 324 into the chamber356 to refresh the pump 326, as illustrated in FIG. 48D. The check valveat the print head, the flow resistance within the trailing tube, or bothwill limit ink from returning to the chamber 356 through the conduit384. Alternatively, a check valve may be provided at the outlet port, orat some other location, to prevent the return of ink through the outletport and into the chamber.

[0206] After a predetermined amount of time has elapsed, the refreshcycle is concluded by rotating the cam 458 back into its disengagedposition and the ink supply typically returns to the configurationillustrated in FIG. 48A.

[0207] However, if the ink supply is out of ink, no ink can enter intothe pump chamber 356 during a refresh cycle. In this case, the backpressure within the ink reservoir 324 will prevent the chamber 356 fromexpanding. As a result, when the cam 458 is rotated back into itsdisengaged position, the actuator 340 returns to its uppermost position,as illustrated in FIG. 48E, and the optical detector 486 is againactivated. Activation of the optical detector immediately after arefresh cycle, informs the control system that the ink supply is out ofink (or possibly that some other malfunction is preventing the properoperation of the ink supply). In response, the control system cangenerate a signal informing the user that the ink supply requiresreplacement. This can greatly extend the life of the print head bypreventing dry firing of the ink jets.

[0208] In some embodiments in may be desirable to rotate the cam 458 tothe disengaged position and remove pressure from the chamber 356whenever the printer is not printing. It should be appreciated that amechanical switch, an electrical switch or some other switch capable ofdetecting the position of the actuator could be used in place of theoptical detector.

[0209] The configuration of the present ink supply is particularlyadvantageous because only the relatively small amount of ink within thechamber is pressurized. The large majority of the ink is maintainedwithin the reservoir at approximately ambient pressure. Thus, it is lesslikely to leak and, in the event of a leak, can be more easilycontained.

[0210] The illustrated diaphragm pump has proven to be very reliable andwell suited for use in the ink supply. However, other types of pumps mayalso be used. For example, a piston pump, a bellows pump, or other typesof pumps might be adapted for use.

[0211] As discussed above, the illustrated docking station 432 (FIG. 44)includes four side-by-side docking bays 338. This configuration allowsthe wall 434, the wall 436 and the base plate 446 for the four dockingbays to be unitary. In the illustrated embodiment, the leaf springs foreach side of the four docking bays can be formed as a single piececonnected at the bottom. In addition, the cams 458 for each dockingstation are attached to a single shaft 460. Using a single shaft resultsin each of the four ink supplies being refreshed when the pump of anyone of the four reaches its minimum operational volume. Alternatively,it may be desirable to configure the cams and shaft to provide a thirdposition in which only the black ink supply is pressurized. This allowsthe colored ink supplies to remain at ambient pressure during a printjob that requires only black ink.

[0212] The arrangement of four side-by-side docking bays is intended foruse in a color printer. One of the docking bays is intended to receivean ink supply containing black ink, one an ink supply containing yellowink, one an ink supply containing cyan ink, and one an ink supplycontaining magenta ink. The mating keys 439 for each of the four dockingbays are different and correspond to the color of ink for that dockingbay. The mating keys 439 are shaped to receive the corresponding keys430 formed on a cap of an ink supply having the appropriate color. Thatis, the keys 430 and the mating keys 439 are shaped such that only anink supply having the correct color of ink, as indicated by the keys onthe cap, can be inserted into any particular locating bay. The matingkeys 439 can also identify the type of ink supply hat is to be installedin the docking bay. This system helps to prevent a user frominadvertently inserting an ink supply of one color into a docking bayfor another color or from inserting an ink supply intended for one typeof printer into the wrong type of printer.

[0213] Constant pressurization of the various ink supply cartridgesdescribed has the following advantages over intermittent pressurization:

[0214] (1) Lower product cost/minimum product complexity by eliminatingany pump station;

[0215] (2) Pressurizing the tubes reduces or eliminates air diffusioninto tubes (depending on pressure level).

[0216] Intermittent pressurization has the following advantages overconstant pressurization:

[0217] (1) Fluid seals and valves do not have to withstand constantpressure, resulting in improved reliability;

[0218] (2) Ink supplies are less expensive, since the plastic shell doesnot need to be as strong.

Conclusion

[0219] The various print cartridges (for example down connect needle, upconnect needle, and septum tower), carriages, and off-axis ink deliverysystems described herein may be used in various combinations to provideink to the nozzles of the printheads in the print cartridges. As oneexample, any of the print cartridges described may be used with eitherthe pressurized or unpressurized ink supply cartridges. The ink supplycartridges may be arranged in a printer for convenient access, ease ofuse, maximum utilization of space, and allowing for the requireddelivered ink volume. The pressure regulator, being integral with theprint cartridge in the preferred embodiment, allows printheadperformance to be independent of the relative heights of the ink supplyand printhead.

[0220] The lowest cost system will typically be one with unpressurizedsupplies. However, pressurization may be required for some situations.This is best understood by considering causes of dynamic and staticpressure changes. The static pressure in the printhead is defined asthat which exists when the printhead is parked and not operating and istypically optimally set to −2 to −6 inches of water column by the springin the regulator. However, if the ink supplies are located more than 6inches below the printhead, then the regulator will always be open(assuming the above setpoint range), and the static pressure will alwaysbe the difference in height. To make matters worse, the pressure ofconcern is dynamic, defined as the pressure experienced in the printheadduring operation. Thus, the actual dynamic pressure will be an evenlarger negative number and will be outside the regulator range.

[0221] Pressurizing the ink supply will solve this problem. This can bedone by the aforementioned method or by using springs to provideconstant ink supply pressure. This can be done to counteract therelative heights, and other factors that affect the dynamic pressuredrop. Factors that increase the dynamic pressure drop include rate ofink usage by the printhead, decreasing tubing diameter, increasingtubing length, and increasing ink viscosity. The pressurization must beincreased until the pressure is entirely controlled by the regulator towithin the print quality driven pressure specification.

[0222] As a result of these design options, the integral pressureregulator offers a wide range of product implementations other thanthose illustrated in FIGS. 1A and 1B. For example, such ink deliverysystems may be incorporated into an inkjet printer used in a facsimilemachine 500 as shown in FIG. 49, where a scanning cartridge 502 and anoff-axis ink delivery system 504, connected via tube 506, are shown inphantom outline.

[0223]FIG. 50 illustrates a copying machine 510, which may also be acombined facsimile/copying machine, incorporating an ink delivery systemdescribed herein. Scanning print cartridges 502 and an off-axis inksupply 504, connected via tube 506, are shown in phantom outline.

[0224]FIG. 51 illustrates a large-format printer 516 which prints on awide, continuous paper roll supported by tray 518. Scanning printcartridges 502 are shown connected to the off-axis ink supply 504 viatube 506.

[0225] Facsimile machines, copy machines, and large format machines tendto be shared with heavy use. They are often used unattended and forlarge numbers of copies. Thus, large capacity (50-500 cc) ink supplieswill tend to be preferred for these machines. In contrast, a homeprinter or portable printer would be best with low capacity supplies inorder to minimize product size and cost. Thus, the product layouts shownin FIGS. 1A and 1B are most appropriate for such smaller form factor orlower cost applications.

[0226] While particular embodiments of the present invention have beenshown and described, it will be obvious to those skilled in the art thatchanges and modifications may be made within departing from thisinvention in its broader aspects and, therefore, the appended claims areto encompass within their scope all such changes and modifications asfall within the true spirit and scope of this invention.

What is claimed is:
 1. A printing system, comprising: a print cartridgehaving a first side and a second side opposite said first side, saidprint cartridge comprising: contact pads on said first side forelectrically contacting corresponding electrodes on a scanning carriagewhen said print cartridge is inserted into said scanning carriage; and afluid interconnect on said second side.
 2. The printing system of claim1 , wherein said contact pads are flush against said first side.
 3. Theprinting system of claim 1 , wherein said fluid interconnect on saidsecond side is a first fluid interconnect, said printing system furthercomprising: a media handling apparatus; an ink source; and a scanningcarriage for scanning across a print zone of a printer, said carriagecomprising: a stall for receiving said print cartridge; a second fluidinterconnect coupled to said ink source, wherein said second fluidinterconnect automatically engages said first fluid interconnect to forma fluid connection when said print cartridge is inserted into saidstall; and said electrodes resiliently biased toward said contact padson said first side of said print cartridge when said print cartridge isinserted into said stall.
 4. The printing system of claim 3 , said printcartridge further comprising a printhead for ejecting droplets of ink ina first direction in response to electronic signals received from saidelectrodes, said fluid connection between said first fluid interconnectand said second fluid interconnect occurring along said first directionsuch that ink from said ink source flows to said print cartridge in adirection substantially opposite said first direction.
 5. The printingsystem of claim 4 , wherein said print cartridge further comprises aninternal chamber for receiving ink from said fluid connection, saidinternal chamber having a regulated pressure, and wherein ink enterssaid internal chamber in said first direction.
 6. The printing system ofclaim 3 , wherein said fluid connection and an electrical connection aresecured simultaneously when said print cartridge is inserted into saidscanning carriage.
 7. The printing system of claim 3 , wherein said inksource comprises at least one replaceable ink supply cartridgereleasably mounted off said carriage and laterally relative to a mediapath of said media handling apparatus.
 8. The printing system of claim 3, wherein said ink source comprises at least one replaceable ink supplycartridge releasably mounted above said scanning carriage.
 9. Theprinting system of claim 4 , wherein said first fluid interconnectcomprises a needle and said second fluid interconnect comprises aseptum, said needle and said septum connect to form said fluidconnection substantially parallel to said first direction.
 10. Theprinting system of claim 3 , wherein said second fluid interconnect ismounted in said scanning carriage to have a degree of movement, saidscanning carriage further comprising a compliant ink conduit connectedto said second fluid interconnect to allow said second fluidinterconnect to have a degree of movement when said first fluidinterconnect is engaged with said second fluid interconnect.
 11. Amethod of providing ink to a print cartridge mounted in a carriage, saidprint cartridge having a first side of a housing having electricalcontact pads for coupling said print cartridge to controller electronicson said carriage, said method comprising: supplying ink from an inksource to a conduit connected to an ink outlet on said carriage;inserting said print cartridge into said carriage to engage a fluidinterconnect on said print cartridge to said ink outlet on saidcarriage, said fluid interconnect being on a second side on saidhousing, opposite said first side, such that ink flows through said inkoutlet and into said fluid interconnect along a flow path separated fromsaid electrical contact pads by said housing; and allowing ink to flowfrom said fluid interconnect and into an internal chamber in said printcartridge.
 12. The method of claim 11 , wherein ink flows from saidinternal chamber to a printhead that ejects droplets of ink in a firstdirection, said ink flows through said ink outlet and into said fluidinterconnect in a direction substantially opposite said first direction.13. The method of claim 12 , wherein ink flows into said internalchamber in a direction substantially parallel with said first direction.14. The method of claim 11 , further comprising supplying ink to saidink source.
 15. The method of claim 14 , wherein said step of supplyingink to said ink source comprises releasably mounting a replaceable inksupply cartridge in fluid communication with said ink conduit.
 16. Anink delivery system for an inkjet printing system, in which a printcartridge having a printhead is removably mounted on a carriage thatscans across a print zone to eject droplets of ink onto media inresponse to electric signals received on electrical contact pads, saidcarriage having a first interconnect member for receiving ink from afixed supply station, said first interconnect member for making areleasable airtight fluid connection to a second interconnect member ona print cartridge that contains said printhead, said system comprising:an off-carriage ink supply containing a reservoir, said ink supply beingadapted to be removably mounted to said supply station; a discharge portin fluid communication with said reservoir; ink contained in saidreservoir which passes out of said discharge port, through a conduit andsaid first interconnect member and into said second interconnect member;and said print cartridge having said electrical contact pads and saidsecond interconnect member on opposing sides of said print cartridge tomaximize a distance between said electrical contact pads and the flow ofink through said first interconnect member and into said secondinterconnect member.
 17. The system of claim 16 , wherein said flow ofink through said first interconnect member and into said secondinterconnect member is in a direction substantially opposite to thedirection of the ejection of droplets of ink.
 18. The system of claim 17, wherein said print cartridge further comprises an internal chamber,said ink flows into said internal chamber in a direction substantiallyparallel to the direction of the ejection of droplets of ink.
 19. Thesystem of claim 18 , wherein said releasable airtight fluid connectionis established automatically when said print cartridge is mounted onsaid carriage.